1. Field of the Invention
This invention relates to a glad-hand pneumatic coupler for rail cars, and in particular to a glad-hand pneumatic coupler which also serves as a data bus coupler.
2. Discussion of Related Art
"Glad-hand" couplers are widely used in the railcar industry for the purpose of establishing connection of pneumatic brake lines extending between railcars. Because of the interchangeability of railcars, and the consequent need for standardization, the essential form of such couplers has remained the same virtually since the invention of the railcar air brake more than a century ago.
A basic feature of railcar glad-hand couplers is hermaphrodicity. Because railcars do not have a preferred front or rear, it is essential that a coupler on one railcar be able to mate with couplers on either end of another railcar.
The standard pneumatic glad-hand coupler includes a rearwardly-extending ferrule on which a pneumatic fluid-carrying hose is fitted and clamped, a disc-shaped elastomeric sealing member having a central opening whose axis is perpendicular to that of the entry ferrule, a flange including a ramp surface, and an extension which serves as a camming surface for causing the sealing member to be compressed against a corresponding sealing member of a mating connector to effect a sealed connection between openings upon relative rotation of the mating couplers.
It has recently been proposed to control pneumatic brake actuation in individual railcars electronically in order to provide better braking control and improve safety. The braking control signals are carried by high voltage insulated data bus cables which, like the conventional pneumatic hoses, extend between the railcars and need to be manually connected following coupling of the railcars. However, because of the requirement that coupling compatibility be maintained throughout the railway system, newer cars with electrical brake actuation must still be able to establish connections via the standard couplings to older cars lacking electronically controllable brakes.
Coupling of the electrical data bus cables can of course be achieved without the need for modifying the standard glad-hand coupler by providing completely separate electrical connections for the data bus. This has the disadvantage of increasing the amount of labor required during coupling of the railcars, and also the chance of an incomplete or improper connection.
On the other hand, while it has been previously proposed to avoid this disadvantage by combining an electrical connector with a glad-hand coupler so that the electrical connection is completed upon completion of glad-hand coupling, the previously proposed electrical connector/pneumatic coupler combinations are unsuitable for use in connection with data buses of the type which carry critical control signals between the railcars cars.
Examples of previous proposals for combining conventional glad-hand pneumatic couplers with electrical connectors dating back to the nineteenth and earlier twentieth century are found in U.S. Pat. Nos. 373,759, 523,847, and 1,224,954. The connectors shown in these patents were designed to carry simple low voltage accessory wires, for bells, phone lines, and the like, and made no provision for dielectric isolation of wires, shock protection, or wire routing, all of which are essential to carry the 240V driving potential of the proposed electronic brake actuators, and which are incompatible with the previous designs.
The present invention addresses this need for a practical glad-hand coupler capable of providing a data bus connection while maintaining dielectric isolation of data lines, shock protection, and wire routing, and that still offers industry-wide compatibility of glad-hand couplers, including the ability to couple with conventional solely-pneumatic couplers.